Heretofore, for example, in a hybrid vehicle, a high-voltage battery has been provided as a drive power supply of a motor. The high-voltage battery obtains a high voltage in such a manner that a secondary battery (storage battery) is composed by connecting a plurality of unit cells, for example, such as nickel-hydrogen batteries and lithium batteries in series to one another.
In the secondary battery, it is necessary to confirm a charged state of each unit cell so as to avoid an overdischarged state or an overcharged state. Therefore, heretofore, a plurality (for example, fifty five) of unit cells are divided, for example, into five blocks (that is, eleven unit cells compose one block), and a voltage of each of the blocks has been measured in real time by a voltage-detecting IC provided for each of the blocks.
In this event, upon measuring the voltage of one block, each voltage-detecting IC has transmitted data through an insulating device to a main microcomputer provided in a low-voltage region (refer to JP 2009-17657 A).
Here, by referring to FIG. 1, a description is made of a conventional circuit configuration between the voltage-detecting IC and the main microcomputer. As illustrated in FIG. 1, heretofore, the respective voltage-detecting ICs provided in a high-voltage region have been connected through the insulating devices to the main microcomputer provided in the low-voltage region.
In particular, in each of the voltage-detecting ICs, there are provided terminals for individually receiving control signals for each of three functions, which are: chip selection; reset; interruption. Accordingly, it has been necessary to provide circuits for transmitting ON/OFF signals to the respective terminals.